Spatial light modulation is used in the fields of optical information processing, projection displays, video and graphics monitors, televisions, and electrophotographic printing. There optical beams are deflected by mirror arrays where it is desired to be able to individually phase adjust the reflected light from each mirror. Because of the large number of mirrors in such arrays it is important to be able to achieve high speeds in the addressing of each mirror as well as accurate control of each mirror""s displacement.
The present invention utilizes a mirror array for use in spatial light modulation. A CMOS circuit is provided on a substrate in an array corresponding to the placement desired for each mirror. A low temperature procedure making use of wet soluble polymer photoresists, sputter deposition and ion etching is then utilized to create a structure above the CMOS circuit comprising a metalized or metal diaphragm supported by flexures from the substrate. The diaphragm and circuit each include opposite plates of a capacitor. The application of a voltage between the circuit and the diaphragm causes the diaphragm to be attracted or repelled by electrostatic forces. In the micron and submicron size of the mirror assemblies and arrays, voltages of a few volts compatible with CMOS circuitry is able to create a half micron displacement.
The fabrication process then uses the same low temperature procedures to create a mirror on top of the diaphragm and supported from it by a single support post. Once released from any polymer used in the fabrication process, the mirror has bending stresses released by a sputter removal of surface layers until a planar surface is achieved. Prior to release, mirror surface roughness can be removed by polishing.